IMO, based on the last news release, any NPV analysis should have been modified to reflect higher costs and / or lower product prices.
IF ZEN sells 25-30% of its graphite into the LIB market, do they sell to a specialty graphite producer or do they build their own spherical graphite plant? If they sell to a specialty producer, the realized price would probably be in the $3,000 - $5,000 range. And if they build their own plant, what are the CAPEX requirements and operating costs? Syrah resources will soon deliver a PEA for a 25,000 tonne per year spherical graphite plant in the U.S. - that will give us an idea of the costs involved.
The cost of purifying a 92% flotation concentrate to + 99.9% Cg purity via caustic bake will likely be north of $2,000 per tonne (that's in addition to the flotation circuit costs) and could even be as high as $5,000 per tonne.
If you want to be conservative, cut your revenues in half and double your costs. But then, the IRR and NPV wouldn't look very good. That's probably what RPA said to Zenyatta last fall.